Both the head and body of Jurgen Kantner were recovered while the troops were conducting combat, search and retrieval operations in Indanan town in the remote southern province of Sulu, colonel Cirilito Sobejana told reporters.

Kantner's remains would be kept in a hospital morgue in Sulu while documents were being prepared to transport the body, said Sobejana, commander of the Joint Task Force Sulu.

The Philippines and Germany have condemned Kantner's killing by the militants who posted a video of the murder after a deadline for a $780,000 (£635,000) ransom passed.

Philippine marines dig as they look for the body of Jurgen Kantner in Sulu provinceCredit:
AFP

The 70-year-old German, who had been held on the small southern island of Jolo, had appealed for help twice in short video messages, saying he would be killed if a ransom was not paid.

His wife Sabine Merz, 59, was fatally shot during the attack when she fought back.

President Rodrigo Duterte has apologised to Germany for failing to save Kantner while insisting that ransoms should not be paid.

The Philippine military has vowed to bring Kantner's killers to justice and to continue operations to free other hostages held by Abu Sayyaf, which had raised tens of millions of dollars from piracy and ransom payments.

Presidential spokesman Ernesto Abella said the government "will leave no stone unturned in squarely addressing the evils of extremism and plain banditry".

"Rest assured these mindless acts will not go unpunished," he said in statement.